Cleaning And Inspection; Cleaning; Inspection - GMC 1990 Light Truck Repair Manual

CLEANING

Do not steam clean drive parts having ground and
polished surfaces such as gears, bearings, and shafts.
These parts should be cleaned in a suitable solvent. All
parts should be disassembled before cleaning.
Parts should be thoroughly dried immediately after
cleaning. Use soft, clean, lintless rags. Parts may be dried
with compressed air. Do not allow the bearings to spin
while drying them with compressed air.
It is very important to carefully and thoroughly inspect
all drive unit parts before reassembly. Thorough
inspection of the drive parts for wear or stress and
subsequent replacement of worn parts will eliminate
costly drive component repair after reassembly.

INSPECTION

AXLE HOUSING
L*
Inspect
• The carrier bore for nicks or burrs that would
prevent the outer diameter of the pinion seal from
sealing. Remove any burrs that are found.
• The bearing cup surfaces for nicks or burrs.
Remove any burrs that are found.
• The housing for cracks. Replace the housing if any
cracks are found.
• The housing for foreign material such as metal
chips, dirt, or rust. Clean as necessary, as outlined
previously.
DIFFERENTIAL
Inspect
L*
Pinion gear shaft for unusual wear.
Pinion gear and side gear teeth for wear, cracks,
scorring, and spalling.
Thrust washers for wear.
The fit of the differential side gears in the differential
case.
The fit of the side gears on the axle shafts.
Differential case for cracks and scorring.
Replace all worn parts.
9 /4-INCH RING GEAR FRONT AXLE 4C2-7
3

CLEANING AND INSPECTION

PINION AND RING GEAR
Inspect
L*
Pinion and ring gear teeth for cracking, chipping,
scoring, or excessive wear.
Pinion splines for wear.
Pinion flange splines for wear.
The fit of the pinion on the pinion flange.
The sealing surface of the pinion flange for nicks,
burrs, or rough tool marks which would cause
damage to the seals' inside diameter and result in
an oil leak.
Replace all worn or broken parts.
Ring and pinion gears are matched sets and are
both replaced any time a replacement of either is
necessary.
BEARINGS
Inspect
L*
Bearings visually and by feel. The bearings should
feel smooth when oiled and rotated while applying
as much hand pressure as possible.
The large end of the bearing rollers for wear. This is
where tapered roller bearing wear is most evident.
Bearing cups for wear, cracks, brinelling and
scorring.
If the rear axle was operated for an extended period
of time with very loose bearings, the ring gear and
drive pinion will also require replacement.
Low mileage bearings may have minute scratches
and pits on the rollers and the bearing cups from the
initial preload. Do not replace a bearing for this
reason.
Bearing caps for cracks or chips.
Bearings and cups are only replaced as sets.
SHIMS
I P Inspect
Shims for cracks and chips. Worn or damaged
shims should be replaced with an equally sized
servise shim.